In order to be able to supply passengers and service personnel with oxygen given a sudden drop of pressure in the cabin, oxygen emergency supply means are available in aircraft. These are located in the passenger region in so-called personal service unit channels or regions which are arranged on the cabin ceiling above the passenger seats. For this, in the personal service unit channels, apart from the air supply of the air conditioning installation, electrical displays, lighting etc., receptacles for accommodating the breathing masks for the supply of oxygen and their activation mechanism are provided. These receptacles arranged in the personal service unit channels comprise a flap on the lower side which opens in the case of a decompression of the passenger cabin, so that the breathing masks, suspended on so-called lanyards drop due to gravity. The supply of oxygen is then activated via the lanyard. This is to be understood as a pull-means which is attached between the mask and the activation mechanism of the oxygen supply. The mask is connected to an oxygen supply with a flexible supply tubing.
The activation mechanism is dependent of the type of oxygen supply. Generally a central or decentralised supply system is applied for the supply of oxygen, depending on the aircraft type or aircraft manufacturer.
The central supply system envisages a central oxygen storage or a means functioning with a molecular sieve, from which oxygen is supplied to all oxygen emergency supply means via a pipe network. The oxygen supply conduits open into the storage containers for the oxygen masks. Here the supply of oxygen may be activated via activation valves, so-called manifolds.
With the decentralised supply system, each storage container has its individual gas generator in which oxygen is produced by way of chemical means. The chemicals required are provided is stainless steel cartridges. An exothermic reaction in the cartridge is activated via an ignition procedure, with which pure oxygen is released.
By way of pulling the lanyard, with the central oxygen supply system the manifod is opened and the supply of oxygen is activated. With the decentralized supply an ignition device of the oxygen generator is actuated via the lanyard. The length of the lanyard defines the height at which the breathing mask hangs down from the supply unit.
By way of applying the oxygen mask, a pulling force is also exerted on the lanyard and thus the activation mechanism for the supply of oxygen is activated. As soon as the lanyard has activated the activation mechanism, a further pulling has the effect that the lanyard separates from the activation mechanism so that the entire length of the flexible supply tubing of the mask is released and the breathing mask may be applied onto the face by a person of a defined size. Further pull-means with grip parts, so-called pull-flags are provided on the breathing masks for sleep boxes of large aircraft. Here it is the case of long cords which are fastened on the mask and ensure that the mask hanging on the lanyard may also be reached when the seat located below it is located in a lying position. At its lower end, the pull-flag is made heavier by weight so that it also reliably falls down.
Large aircraft may have a seating arrangement which envisages seating rows of four or more seat locations lying next to one another. In these seat rows, the oxygen masks must also be readily reachable by the passengers on the outer seat locations which may be arranged next to and not below the personal service unit channel.
One solution for such masks which are to be arranged next to the personal service unit is represented in the U.S. Pat. No. 4,154,237. Here, after opening the mask container, apart from the freely-hanging breathing masks, breathing masks are also released which suspended on a rail, are extended horizontally to the outer seat positions. In this manner the breathing masks hang on the flexible supply tubing over the lateral seats from which the breathing masks would otherwise be poorly reached.
The disadvantage with this arrangement is the fact that the lanyards required for activating the supply of oxygen, as in the past, fall downwards out of the mask containers and are poorly accessible at the outer seat positions. Furthermore, on account of the momentary loading on applying the oxygen masks, the rail must be designed in a very stable manner which necessitates an increased weight. In aircraft with which the baggage compartments or hat compartments, so-called hat racks which are arranged laterally next to the personal service unit channel are provided in a lowerable manner, a lowered hat rack would completely prevent the application of this arrangement since it would block the extending of the rails and the rail would be retained with the oxygen masks in the personal service unit.